Question

Shape of 3-D view of tRNA is
A. Z-shaped
B. X-shaped
C. Y-shaped
D. L-shaped

Answer 1

Ribonucleic acid is one of the important biological molecules involved in various molecular processes of living organisms like protein synthesis, transfers of genetic instructions from the DNA which are important for various processes. RNA carries genetic information instead of DNA in viruses.

Complete answer:
DNA and RNA are two types of nucleic acids having different sugars – DNA has deoxyribose as its sugar and RNA has only ribose. Structure of DNA is double helical but an RNA can have a single stranded structure. Due to its single stranded structure RNA can fold back onto itself in a number of ways making different structure which exhibit different functions like:
-mRNA or messenger RNA – It plays an important role during transcription as it carries genetic information from the DNA in the form of codons (which are triplets formed of nucleotides) from the nucleus of the cell to its cytoplasm. Its most important function is to transcribe the genetic code in a readable format which is used to make proteins.
-rRNA or ribosomal RNA – This type of RNA contains two major components – small subunits which help in reading the RNA and large subunits which help in the formation of polypeptide chains by joining amino acids. Its major function is to help the translation of mRNA into proteins.
-tRNA or transfer RNA – They are the smallest among all the forms of RNA and have an important role in the process of translation where they transfer amino acids for the protein synthesis.

-Structure of tRNA
It has a unique structure like that of a clover leaf due to the presence of four helical stems which are stabilised by strong hydrogen bonds present in between the nucleotides. They are made up of around 60 to 95 nucleotides but mostly around 75 nucleotides are found though. In the 3 dimensional structure it adopts the L shape having an acceptor on one end and anticodon on the other end.

Hence, the correct answer is option (D).

Additional information:
-Out of the total RNA present in the cell 5% of it is mRNA, 80% is rRNA and the rest is tRNA.
-Clover leaf structure of tRNA is a secondary structure which converts to L shaped tertiary structure by the coaxial stacking of helices.
-The acceptor present on one end is a CCA tail which is made up of cytosine-cytosine-adenine present at the 3’ end.
-Z shape is found in DNA, it is a zigzag pattern in which the DNA helix winds towards the left hand side.
-X shape is found in the sex chromosomes mainly and not in the structure of DNA or RNA.
-Y shape is seen in Y RNA which plays an important role in DNA duplication and inhibition of Ro60.

Note: All the amino acids have their specific tRNA which transfer them to the growing amino acid chain during protein synthesis, they also act as an adapter during the mRNA translation into proteins because of which they are known as adapter molecules also.